1. Field of the Invention
The present invention relates to an organic electro luminescence device, and more particularly, to an active matrix organic electro luminescence device panel in which a peripheral circuit is integrated and mounted on a second substrate not having a pixel.
2. Description of the Related Art
Cathode Ray Tube (CRT) display devices and liquid crystal display (LCD) devices are the most commonly used display devices. However, as a flat panel display devices are increasingly required to occupy smaller spaces, be lighter in weight and/or have a larger display size, an organic electro luminescence device (hereinafter, referred to as “organic EL device”) is being rapidly developed as a viable flat panel display device. Several products have been delivered to a market using organic EL technology. Further, in recently developed organic EL devices, an active matrix organic light emitting diode (AMOLED) has been used to enable individual control a pixel, which defines the elementary unit forming a picture.
Each AMOLED includes a thin film transistor and an ITO electrode (anode) as a pixel electrode, which are arrayed in matrix on a transparent substrate. An organic emission layer, which emits light of a predetermined wavelength, and an upper electrode (cathode) are formed on the pixel electrode. The structure of the AMOLED is encapsulated by a metal to prevent degradation of the organic emission layer due to oxygen and moisture.
More particularly, the AMOLED includes an organic electro luminescence layer formed between the anode and the cathode. The anode is a transparent electrode of a material such as ITO, and the cathode uses a metal (Ca, Li, Al:Li, Mg:Ag and the like) with a low work function. If a forward voltage is applied between the anode and the cathode, holes and electrons are injected into the anode and the cathode. The injected holes and electrons are combined to form excitons. The excitons are radiatively recombined causing an electro emission phenomenon.
The organic electro luminescence layer can be formed of a single material, but is generally formed of several organic materials to have a multi-layer structure. That is, because the holes and the electrons can be effectively transmitted to the organic emission layer (EML) in the organic material due to the large mobility difference between holes and electrons when the hole transport layer (HTL) and the electron transport layer (ETL) are used. The densities of the holes and the electrons are balanced in the organic emission layer, thereby enhancing emission efficiency. Further, according to the particular application, a hole injection layer (HIL), such as a conductive polymer, is additionally inserted on the anode and the HTL to lower an energy barrier against hole injection. Furthermore, a buffer layer (EIL), such as LiF, is added with a small thickness of about 5–10Å between the cathode and the ETL to lower an energy barrier against electron injection, thereby enhancing the emission efficiency and lowering a driving voltage. Additionally, the organic material used for the organic emission layer inserted between the both electrodes has an advantage in that a composition route is simple to facilitate various types of material composition and enable color tuning.
FIG. 1 is a sectional view illustrating a related-art AMOLED panel.
Referring to FIG. 1, the AMOLED panel includes a plurality of pixels 13, which is arrayed in matrix on a first substrate 10. Each of the pixels 13 includes a thin film transistor 11 and an Indium Tin Oxide (ITO) as a pixel electrode 12. The pixel 13 is formed at a region, which is defined between a plurality of gate lines (not shown) and a plurality of data lines (not shown). An organic electro luminescence layer 18 and a cathode 19 are sequentially formed on the pixel electrode 12. As described above, the organic electro luminescence layer 18 includes a hole injection layer (HIL) 14, a hole transporting layer (HTL) 15, an organic emission layer 16 of red, green, blue, and an electron injection layer (EIL) 17. Further, a desiccant 21 is adhered on an inner surface of the second substrate 20 within a space defined by the second substrate 20 to prevent the emission characteristics of the organic emission layer 16 of the organic electro luminescence layer 18 from being degraded and to prevent the cathode 19 from being lifted-off. The desiccant 21 functions to eliminate moisture. Here, the second substrate 20 functions to encapsulate the organic EL structure, and is sealed with the first substrate 10 by a sealant 22.
The AMOLED panel includes drivers and the like for applying a predetermined signals to the gate lines and the data lines. A structure of the related-art AMOLED panel having drivers and the like mounted thereon will be described with reference to FIG. 2. FIG. 2 is a schematic plan view illustrating a related-art AMOLED panel.
Referring to FIGS. 1 and 2, in the related-art AMOLED panel, a tape carrier package (TCP) 24 with the driver 23 is attached to one side or both sides of the first substrate 10. At this time, the TCP 24 is concurrently attached to the AMOLED panel and a printed circuit board (PCB) substrate 25 having a timing controller and the like to transmit a gate signal and a data signal from the PCB substrate 25 to the AMOLED panel.
In the above-constructed related-art AMOLED panel, the first substrate 10 includes a TCP pad forming part to which the TCP is attached, and a wire part for connecting between a TCP pad and a pixel array part, thereby causing a complicated structure at an edge region of the first substrate, whereas the second substrate 20 simply functions only to attach the desiccant 21 and provide a sealed space. Accordingly, the related-art AMOLED panel structure has a disadvantage in that the peripheral circuit of the panel is entirely mounted on the PCB. As a result, a wire structure of the first substrate is also complicated, thereby limiting the overall compactness of the panel.